PDO::exec or PDO::execute?

Question

I use PDO to connect to my database and I don't know which method is better than the other one for UPDATE, DELETE and INSERT, PDO::exec or PDO::excute. Which should I use?

Answer 1

Although both methods have a similar naming (exec,execute) they're meant to be used in different scenarios:

1. exec is used to get the number of affected rows.

   /**
    * (PHP 5 &gt;= 5.1.0, PECL pdo &gt;= 0.1.0)<br/>
    * Execute an SQL statement and return the number of affected rows
    * @link http://php.net/manual/en/pdo.exec.php
    * @param string $statement <p>
    * The SQL statement to prepare and execute.
    * </p>
    * <p>
    * Data inside the query should be properly escaped.
    * </p>
    * @return int <b>PDO::exec</b> returns the number of rows that were modified
    * or deleted by the SQL statement you issued. If no rows were affected,
    * <b>PDO::exec</b> returns 0.
    * </p>
    * This function may
    * return Boolean <b>FALSE</b>, but may also return a non-Boolean value which
    * evaluates to <b>FALSE</b>. Please read the section on Booleans for more
    * information. Use the ===
    * operator for testing the return value of this
    * function.
    * <p>
    * The following example incorrectly relies on the return value of
    * <b>PDO::exec</b>, wherein a statement that affected 0 rows
    * results in a call to <b>die</b>:
    * <code>
    * $db->exec() or die(print_r($db->errorInfo(), true));
    * </code>
    */
   public function exec ($statement) {}
   

   Example:

   $myQuery = "UPDATE users SET email = 'testing'";
   $affectedRows = $db->exec($myQuery);
   

2. execute is used when you want to pass an array of parameters to be bind in the query.

   /**
    * (PHP 5 &gt;= 5.1.0, PECL pdo &gt;= 0.1.0)<br/>
    * Executes a prepared statement
    * @link http://php.net/manual/en/pdostatement.execute.php
    * @param array $input_parameters [optional] <p>
    * An array of values with as many elements as there are bound
    * parameters in the SQL statement being executed.
    * All values are treated as <b>PDO::PARAM_STR</b>.
    * </p>
    * <p>
    * You cannot bind multiple values to a single parameter; for example,
    * you cannot bind two values to a single named parameter in an IN()
    * clause.
    * </p>
    * <p>
    * You cannot bind more values than specified; if more keys exist in
    * <i>input_parameters</i> than in the SQL specified
    * in the <b>PDO::prepare</b>, then the statement will
    * fail and an error is emitted.
    * </p>
    * @return bool <b>TRUE</b> on success or <b>FALSE</b> on failure.
    */
   public function execute (array $input_parameters = null) {}
   

   Example (of course this might be an UPDATE or DELETE query as well):

   $myQuery = 'SELECT * FROM users WHERE username = :username';
   $params = array(':username' => 'admin');
   $db->query($myQuery)->execute($params);
   

3. query returns a PDOStatement object

   /**
    * (PHP 5 &gt;= 5.1.0, PECL pdo &gt;= 0.2.0)<br/>
    * Executes an SQL statement, returning a result set as a PDOStatement object
    * @link http://php.net/manual/en/pdo.query.php
    * @param string $statement <p>
    * The SQL statement to prepare and execute.
    * </p>
    * <p>
    * Data inside the query should be properly escaped.
    * </p>
    * @return PDOStatement <b>PDO::query</b> returns a PDOStatement object, or <b>FALSE</b>
    * on failure.
    */
   public function query ($statement) {}
   

For more information you can visit the PHP Docs or in case you're using PHPStorm you can go though the source code of the PDO.php class.